This invention relates to track assemblies for track-type vehicles. In particular, this invention relates to an improved impact lug for such assemblies which minimizes metal-to-metal contact between the track and frame elements thereof during operation of the vehicle, and imparts improved wear and operating characteristics to the assembly.
Conventional endless tracks for use with track-type vehicles such as crawler tractors comprise a series of track links interconnected by pins fitted with an external bushing. In such a construction, the track links have an inner rail surface upon which the track rollers and idler wheels roll. The pin and bushing connections of these conventional prior art structures provide a drive means for coaction with a chain-driving sprocket whereby the track is forcibly driven by rotational movement of the sprocket.
Although such a track construction has gained wide acceptance, it is subject to several shortcomings, such as noise created by the bushings impacting upon the drive sprocket, and the rail surfaces impacting on the idler. Such conventional structures are also subjected to a high rate of wear and power losses due to these impactions and due also to the scrubbing action of the bushings against the sprocket as the track is driven.
A recent development in the art of endless tracks for track-type vehicles is the provision of a drive lug located on the track shoes intermediate the pin and bushing connections to assist the bushings in driving the track. Although these mid-pitch drive lugs have been somewhat effective in substantially eliminating a number of the disadvantages associated with conventional endless tracks, other disadvantages, such as high noise and wear levels, have not been satisfactorily overcome. Exemplary of prior art attempts to reduce noise, wear and other shortcomings of endless track assemblies include the mid-pitch drive lugs described in U.S. Pat. Nos. 3,563,614; 3,567,294; and 3,680,929; the cushioned assembly and related components described in U.S. Pat. Nos. 2,338,817 and 3,504,562; and the miscellaneous improvements described in U.S. Pat. Nos. 3,486,574 and 3,504,951.
Cross reference is made to U.S. application Ser. No. 416,828, to Boggs et al. filed Nov. 19, 1973, .Iadd.now Pat. No. 3,889,550 .Iaddend.which illustrates another solution to solve the problem.
Typically, these and other endless track assemblies presently in use fail to meet the stringent noise limitations for track-type vehicles imposed by Federal legislation.